Layering ratio planner.

Worked example

You normally wear 5 sprays and want a 2:1 layer. The exact split is 5 x 2/3 = 3.33 and 5 x 1/3 = 1.67 sprays; rounding to whole sprays gives 3 and 2. At 0.1 ml a spray that is 0.3 ml and 0.2 ml, so a 100 ml bottle of the first lasts 100 / 0.3 = 333 wears and a 50 ml bottle of the second lasts 50 / 0.2 = 250 wears.

How it works

Each fragrance gets total sprays x its parts / sum of parts. Whole sprays are assigned with largest-remainder rounding so the shares always add back to your total. ml per fragrance = sprays x ml per spray. Wears per bottle = bottle ml / ml per wear of that fragrance.

What this is not. There is no published standard for layering ratios and no rule for which scents go together; 1:1 and 2:1 are common starting points, not laws. Test on skin or a card before wearing a new combination.

Sources and basis: pure arithmetic on the numbers you enter; no published figure is used, and any default marked as an assumption or rule of thumb is not a published standard.

FAQ

How many sprays of each perfume when layering?

Keep your total sprays about what you wear normally and split them by ratio. For 5 sprays at 2:1 that is 3 and 2. Enter yours above.

What is a good layering ratio?

There is no published standard. 1:1 and 2:1 are common rules of thumb, with the stronger or heavier scent usually getting the larger share. Adjust to taste.

Does layering use more perfume?

Not if you keep the total sprays the same. Each bottle then lasts longer because each only supplies part of the sprays; the wears-per-bottle figure shows by how much.

Can I layer three fragrances?

Yes. Fill the third ratio part, for example 2:1:1. With a small total the fragrance with the smallest share may get only one spray, or none.